Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thu sach » thuat sach, thuoc sach, thu hoach
van hanh » van thanh, ban hanh, van anh
hanh ki » hanh vi, hanh ky, hanh kien
xuc van » duc van, luc van, vuc van
tu sach » su sach, te sach, tu cach
vu dang » su dang, vu quang, cua dang
dang ma » dang mau, dang mam, dang mat
ma hoi » mai hoi, xa hoi, ma hoa
va cao » va cac, va co, va dao
va cam » va cham, va cac, va cai
ki su » ky su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) OR (thu sach)) vu dang ma hoi. hieu ((va cam) or (va cao)) xuc van hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) vu dang ma hoi. hieu ((va cam) OR (va cao)) xuc van hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) vu dang ma hoi. hieu ((va cam) or (va cao)) xuc van hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) vu dang ma hoi. hieu ((va cam) or (va cao)) xuc van hanh ki su triet*.